Copper alloy for electronic material and method of manufacture for same

Abstract

There is provided a copper alloy for electronic material which exhibits excellent plating uniformity. A copper alloy for electronic material, wherein, when its cross section parallel to a rolling direction is observed by SIM, an area ratio of amorphous structure and crystal grains having a grain size of less than 0.1 μm at a depth range of 0.5 μm or less from the surface is 1% or less, and a ratio of the number of crystal grains having a grain size of at least 0.1 μm and less than 0.2 μm to the overall number of crystal grains having a grain size of at least 0.1 μm at a depth range of 0.2-0.5 μm from the surface is 47.5% or more.

1 . A copper alloy for electronic material, wherein, when its cross section parallel to a rolling direction is observed by SIM, an area ratio of amorphous structure and crystal grains having a grain size of less than 0.1 μm at a depth range of 0.5 μm or less from the surface is 1% or less, and a ratio of the number of crystal grains having a grain size of at least 0.1 μm and less than 0.2 μm to the overall number of crystal grains having a grain size of at least 0.1 μm at a depth range of 0.2-0.5 μm from the surface is 47.5% or more. 
     
     
         2 . The copper alloy for electronic material according to  claim 1 , wherein, when its cross section parallel to a rolling direction is observed by SIM, a ratio of the number of crystal grains having a grain size of at least 0.1 μm and less than 0.2 μm to the overall number of crystal grains having a grain size of at least 0.1 μm at a depth range of less than 0.2 μm from the surface is 57.5% or more. 
     
     
         3 . The copper alloy for electronic material according to  claim 1  or  2 , wherein the copper alloy is phosphor bronze, titanium copper or Corson alloy. 
     
     
         4 . A method of manufacture for a copper alloy for electronic material, comprising:
 Step 1) polishing a surface of copper alloy base material with an abrasive of count #600-8000 to form a damaged layer having a sufficient thickness such that, when its cross section parallel to a rolling direction is observed by SIM after Step 2), a ratio of the number of crystal grains having a grain size of at least 0.1 μm and less than 0.2 μm to the overall number of crystal grains having a grain size of at least 0.1 μm at a depth range of 0.2-0.5 μm from the surface becomes 47.5% or more, and then Step 2) further polishing with an abrasive having a particle size (d50) of 0.01-0.5 μm to remove amorphous structure and fine crystal grains having a grain size of less than 0.1 μm from the damaged layer such that, when its cross section parallel to a rolling direction is observed by SIM, an area ratio of amorphous structure and crystal grains having a grain size of less than 0.1 μm at a depth range of 0.5 μm or less from the surface is 1% or less, and a ratio of the number of crystal grains having a grain size of at least 0.1 μm and less than 0.2 μm to the overall number of crystal grains having a grain size of at least 0.1 μm at a depth range of 0.2-0.5 μm from the surface is 47.5% or more.   
     
     
         5 . The method of manufacture according to  claim 4 , wherein the abrasive used in Step 1 is made of silicon carbide, and the abrasive used in Step 2 is made of aluminum oxide or colloidal silica. 
     
     
         6 . The method of manufacture according to  claim 4  or  claim 5 , wherein the polishing in Step 1 and Step 2 are performed by buffing. 
     
     
         7 . A plated product provided with a plating film on a surface of the copper alloy according to any one of  claims 1 - 3 . 
     
     
         8 . The plated product according to  claim 7 , wherein the plating film contains any one or more of Ni, Sn and Ag.